Merge tag 'fsnotify_for_v6.18-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs

Pull fsnotify fixes from Jan Kara:

 - Stop-gap solution for a race between unmount of a filesystem with
   fsnotify marks and someone inspecting fdinfo of fsnotify group with
   those marks in procfs.

   A proper solution is in the works but it will get a while to settle.

 - Fix for non-decodable file handles (used by unprivileged apps using
   fanotify)

* tag 'fsnotify_for_v6.18-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
  fs/notify: call exportfs_encode_fid with s_umount
  expfs: Fix exportfs_can_encode_fh() for EXPORT_FH_FID

Author: torvalds

fs/notify/fdinfo.c

@@ -17,6 +17,7 @@
 #include "fanotify/fanotify.h"
 #include "fdinfo.h"
 #include "fsnotify.h"
+#include "../internal.h"
 
 #if defined(CONFIG_PROC_FS)
 
@@ -46,7 +47,12 @@ static void show_mark_fhandle(struct seq_file *m, struct inode *inode)
 
 	size = f->handle_bytes >> 2;
 
+	if (!super_trylock_shared(inode->i_sb))
+		return;
+
 	ret = exportfs_encode_fid(inode, (struct fid *)f->f_handle, &size);
+	up_read(&inode->i_sb->s_umount);
+
 	if ((ret == FILEID_INVALID) || (ret < 0))
 		return;
 

include/linux/exportfs.h

@@ -320,16 +320,17 @@ static inline bool exportfs_can_decode_fh(const struct export_operations *nop)
 static inline bool exportfs_can_encode_fh(const struct export_operations *nop,
 					  int fh_flags)
 {
-	if (!nop)
-		return false;
-
 	/*
 	 * If a non-decodeable file handle was requested, we only need to make
 	 * sure that filesystem did not opt-out of encoding fid.
 	 */
 	if (fh_flags & EXPORT_FH_FID)
 		return exportfs_can_encode_fid(nop);
 
+	/* Normal file handles cannot be created without export ops */
+	if (!nop)
+		return false;
+
 	/*
 	 * If a connectable file handle was requested, we need to make sure that
 	 * filesystem can also decode connected file handles.